Fluid displacement device



Nov. 1l, 1952 v. D. BARKr-:R

FLUID DISPLACEMENT DEVICE 5 Sheets-Sheet l Filed May lO, 1945 M a mf s@Nm w N M w Nm Nm mm m r m. mm NQQDN .iv NME: @nu R ::MH wm o .f r l mwIUI mmm l @NIW Lnv Y Il f l bv O 'l &\l ,l 1 Q, H: @n q mm. W :Hl uw NNm5 r .l S o II Il D m i a wi m TFM n RP `Y O E TB N m. fm WD WT. q V

V. D. BARKER FLUID DISPLACEMENT DEVICE Nov. 11, 1952 5 Sheets-Sheet 2Filed May l0, 1945 @moww l INVENTOR Virgil D o'zrker BY '/MTNEYS V. D.BARKER FLUID DISPLACEMENT DEVICE Nov. 1l, 1952 Filed May 1o, 1945 5Sheets-Sheet 5 INVENT R 'Virgil D Barker Nov. 11, 1952 v. D. BARKER2,617,360

FLUID DISPLACEMENT DEVICE Filed May 1o, 1945 5 Sheets-Sheet 4 INVENTORNov. ll, 1952 v. D. BARKER 2,617,360

FLUID DISPLACEMENT DEVICE lll`\ fr, J

2 d f '435 h N a 1- -v C j( a I? q g, I J f vq h 7 1 a 5 l 7 9 s 70, 2l/ a` 4, 6 7 8f 70 10 ,A 4 /l/ ,Y ,X X 2 f 9 2 4, 1 3 6 5 I,9// 7 9 f' 1s f 5 f 7 l, 5 f f L y f L f W13 wwf/'Wsw Patented ov. 1975-72 unirsi)Vf sTArEfs PATENT, OFFICE i FLUID DISPLACEMENT DEVICE.

VrgiltD. Barker, WesteltLN. J. AllplicationMay 10,194:5,7-S7er'ia1No.'593,'027

21 Claims. l

This invention relates to iluid pumps, Iand; it will be disclosed anddiscussed in that connection. Various aspectsof theinventionare, how.-ever, applicable -to iiuid displacement, devices gen.- erally,.including fluid motorsV andr fluidvpower transmissions.

In the preferred form hereindisclosed, theinvention is concernedwithavariable displacement high pressure pump, and more` particu1arly,'witha pump having a rotatable cylinder. blockl pro.- vided-with cylinder.boresr Whose axes are parallel to .the aX-is of rotation. of .thecylinder block.. In each cylinder bore opposedpistons are .operable toYeffect pumping. action. Normallystationary cam members cause thepistons to havepumping action as thecylinder blockis rotatedwithin apump housing, these cam membersbeingrelativee ly adjustableito shift thephase ofthe piston cyclesand to thereby control the'pump output.

The related prior art pumps of which I am aware, have yinvolved meansfor causing reciproeating action of the pistons such that thepistonmotionv has been AVirtually sinusoidal,"or vharmonic. Thus, the pistoncycles are such that the rate of displacement of any piston is neverzero for anysubstantial proportion of a, piston cycle, and it. istherefore necessary that communication WithV each cylinder bore beshifted almost in-i stantly from connection to an inlet'. to connectionwith an outlet, or "vice versa.. The valving action has .beenaccomplishedy generally. by' some form'lofrotary motion between two iiat'or cy-Y lindrical surfaces `having coacting` .ports for al;- ternateconnection ofthe cylinder bores .with inlets and; outlets. This meansthat thequick shifts from inlet to outlet can be'obtained'only if themain inlet and outlet'ports are sealed from veachA other by very shortmoving seals';"an d such arrangements tend to leak iuid'underhighpressuresgeven though the coacting parts of the valve mechanism' areconstructed tovery close tolerances. If the seallengthsare increasedgthecylinder bores are then not completely lled on their suction strokes,-or' the pistons unduly com'- press-thefluid before the outlet port isopened, resulting-in excessive vibration, noise," lossof powerfhighlstresses --anda h-igh degree-ofwear on parts subjectedto 'bearing-Ap-ressures'.

A general object cf the presentiinvention is to provide va pum-p-offsuch constructionthat these defects or disadvantagescan bef-suitablyeliminatedl or minimized and in thepump herein disclosedthepiston'motions are such that the eiTective displacement from anycylinder'borejmaybe conveniently reduced to zero for a suicientpro-Vportion of the cycle to facilitate the usejo'f longer sealsjandadequatevalving' cycles.

'Ifheiinveption Hincludes within its 'purview a purnpjemployng a pair'of coordinated'cams to produce a vsmoothperiodic. pistonmotion Whichisnot a true harmonic. lilaclficanji vmay be so con,- structed `andarranged with reference tothe num; bers of pistonsV .and cylinder boresas. toiresult in 'uniform puvlsationlessA flow 'and' continuous balanceof all` hydraulic inertia andv bearing forces, at various ovv, rates.V

The inventicn aISO provides a. pump in which the'valving is accomplishedby the 'enacting m0- uons. of .opposed pistqnsiin. a, commoncylnderbore, 'the cylinder boreincorporating inletjand outletV` ports in itsWall. These ports 'are opened and closed 'inthe proper sequence by thepistons themselves-and, consequently', rany need for sepa;-ratejvalveelements is eliminated. In."the valv- 'ing of the' pump hereindisclosed the necessary close ts betweenpistons andcylinder' boresinherently. Iand automatically function tojp-rovide close t valving atno eXtra cost in precise' manufacturing operations.

Control of the rate and direction` of output fluidjow is, accomplishedthrough veffective uti lization of the'arrangementof opposedpistons ineach. of a plurality of cylinder bores. .The cyl,- inderbores are.arranged with .their axes parallel to 'the axis of pump' rotation, andthe rcciprof 'catory'relative motion.V between4 the pistonsandthe'cylinpder block is attained bythe use of .apair of cams 'which arenormally stationary.A All' for" thepistons Whichface in one directionareV controlledby oneof the cams,7 and allof thepistons which faceinthe0the1'-direction are controlled by, theotherfcam. The; cams aresimilar,. but of vopposed contour, and preferably .cause each piston toexecutethes same .periodic motioninvolving dwell, acceleration, strokeandA deceleration. All' elements 'of piston motion are repetitive inpattern and magnitude,

Amongjthe objects of the invention accom.- plished by the hereindisclosed pump are: increased mechanical andr volumetric efficiency;marked. reduction of Vuid lossdue to leakage; balance of forcesimposedby hydraulic orinertia loads Withinv the pump, thus eliminating lthenecessity' for large and costly bearings; .reduction of parts; componentparts of such construction that they may be machined to closevtolerancesby available manufacturing methods at comparatively low cost; a highdegree of sensi.- tivity of the pump in response to control impulsesfrom simple control mechanisms; uniform'rates 3 of flow at allmagnitudes of displacement; and marked reduction of vibration and noise.

My invention is clearly dened in the appended claims. In the claims, aswell as in the description, parts are at times identified by specificnames for clarity and convenience, but such nomenclature is to beunderstood as having the broadest meaning consistent with the contextand with the concept of my invention as distinguished from the pertinentprior art. The best form in which I have contemplated applying myinvention is illustrated in the accompanying drawings forming part ofthis specification, in which:

Fig. 1 is a longitudinal vertical section of the pump taken in generalon the line I I of Fig. 2;

Figs. 2, 3, 4, 5 and 6 are vertical sectional views taken in general onlines 2 2, 3 3, 4 4, 5 5, and 6 6, respectively, of Fig. 1;

Figs. 1, 8, 9 and 10 are views illustrating one of the cams used toactuate the pistons. These views show the cam before assembly, and theposition of the cam in these views bears no relation to the assembledposition shown in Figs. l, 2 and 5. Fig. '7 is an elevation. Fig. 8 is asection on line 8 8 of Fig. 7. Fig. 9 is an edge view looking from thebottom of Fig. '1. Fig. 10 is a perspective View.

Fig. 11 is a partly diagrammatic view, including an enlargedlongitudinal section of one of the pistons;

Fig. 12 is a diagrammatic development illustrating the reciprocation ofthe pistons, the Valving, and Variable displacement; and

Fig. 13 is a diagram indicating the uniform rate of flow for anyeffective displacement.

The pump shown in the drawings has ten pairs of opposed pistons, onepair operating in each of ten cylinder bores. Fig. 1 shows two pairs ofthe pistons in an instantaneous position. For convenience and clarity,the actual position of the pistons is disregarded in Figs. 4, 5 and 6;and in these figures each pair of opposed pistons is assumed to be inthe same position as the two pairs shown in Fig. 1.

The housing of the pump shown consists of three main parts. The centralhousing section. designated as a whole by I5 (Fig. l), is formed with amain bore I6 within which the cylinder block 49 rotates in spacedrelation. Housing I5 also has cam counterbores I1 and I8, a bore I9 forthe control piston, and attachment flanges 26 and 2I. The rear housingor housing section, designated as a Whole by 22, is provided with anattachment ilange 24 secured in fluid-tight relationship to the flange20. Housing section 22 also has a cam counterbore 25, a pintle bore 26,fluid passages 21 and 28 (see also Fig. 3) and a control piston bore 29aligned with the bore I9 of the central housing section I5. Thecounterbore 25 combines with the counterbore I1 to form a recess for thecam 39. The rear housing section 22 is also formed with legs or supports3l, 3| for mounting the pump (see also Fig. 2). The front housingsection, designated as a whole by 32, is formed with a ilange 34 that issecured in duid-tight relationship to the flange 2| of the centralhousing section I5. The front housing section 32 is further formed witha cam counterbore 35, which combines with the counterbore I8 in thecentral housing section to form a recess for the cam 46. Housing section32 also has a bearing counterbore 36 and a control piston bore 31, aswell as opposite legs or supports 38 (one shown).

The three housing sections I5, 22 and 32 are held in pressure-tightrelationship by a suitable number of cap screws 39; and rear and frontcover plates 4I and 42 are clamped to the rear and front housings 22 and32 by a suitable number of cap screws 44. While sealing gaskets may beemployed, I prefer that the mating faces of the housing ilanges, and themating faces at the cover plates, be so machined and ground that leakagecan be prevented without the use of gaskets.

Disposed centrally of the pump is a pintle provided withlongitudinally-bored pairs of fluid passages 46, 46 and 41, 41 thearrangement of which is indicated in Figs. l, 2, 3, 4 and 6. Thepassages 46, 46 and 41, 41 may be blind or deadend passages, bored fromone end of the pintle and having their ends closed by plugs 48. Theseplugs will ordinarily be slotted or otherwise recessed to receive a toolfor screwing them home. but for clarity such recessing is not shown.

Pintle passages 46, 46 both communicate with horseshoe passage 21 in thehousing section 22, and this horseshoe passage may be connected at 21a(Fig. 3) to a source of fluid supply. The rotatable cylinder block,designated as a whole by 49, is provided with an annular groove 50 whichcommunicates with passages 46, 46, the communication being throughtransverse moonshaped cut-outs 52, 52 in the pintle (see also Fig. 4).The annular groove 50 also communicates with the left half of each ofthe cylinder bores 5I, the groove being so positioned that the porttherefrom to each cylinder bore will be opened and closed by theleft-hand piston as it reciprocates.

An outlet uid line 28a (Fig. 3) is connected to outlet passage 28 inhousing section 22; and outlet passage 28 is in turn connected to thenearer of the fluid passages 41 in the pintle. Through crosswise bore41a the outlet passage 28 is also connected to the farther fluid passage41. The right-hand end of each of the longitudinal uid passages 41, 41is in communication, through transverse moon-shaped cut-outs 53, 53(Fig. 6) with an annular outlet groove 54 formed in the cylinder block49. The groove 54 is so positioned that the port therefrom into each ofthe cylinder bores 5I will be opened and closed by the right-hand pistonas it reciprocates.

The cylindrically surfaced pintle 45 is accurately machined and groundto form a tight iii; in the rear housing bore 26. Assembly may be bypressing pintle 45 into bore 26, or by shrinking housing 22 onto thepintle 45. The pintle has a very close running fit in the bearing 55 ofthe cylinder block 49.

Each of the cylinder bores 5I is provided with two grooves, 50' and 54',annular with respect to the cylinder bore axis, to prevent hydraulicside thrust of the pistons against the cylinder bore walls when thepistons pass through the annular passages 50 and 54. Each of thepistons, designated as a whole by 56 (see also Fig. 1l) may beconsidered as consisting of a working piston portion 51 and an integralcrosshead portion 58 of larger diameter; and these portions have closerunning fits with differentially bored portions of the cylinder bores5I.

Mounted in each crosshead 58 is a ball driver or cam follower 59, eachball driver being seated in a socket having a, spherical surface. Thetwo pistons in each cylinder bore are biased apart at all times by acoil spring 60. Each such coil spring is substantially housed within apair of 51' opposed'working pistonse. 56, `56ffwithsthe'fends. of eachKVspring abutted against the shoulders 6| (Fig. 11) 'nea'r' the junctionof each'workin'gfpiston jand its crosshead` 58.

Coacting with the pistons 56 are the'fcycle 'camsr 30 'and 40,'positioned both axially and radially-byv counterbores 11,25and I8,35,'respectively. The cams 30 and 40 are similarly arranged, andtheircontours are :so matched or `coordinated that' as the cylinderblock'rotates the' cams effectthedesi'redcycle of reciprocation of eachpair (and While lthen all pairs) of the opposed pistons. cam'sarenormally stationary, they are' permitted angular' phaseshiftin'gmovement which `for each cam is limited by a stop pin 62 thatprojects/into cam reces '64 (see also Figs.' 2 and 5). Eachcam, in azonediametricallyv opposite its recess =64`is provide'd'with 'a number'ofhelical gear' teethat.

65.` v'In camA 39the high zonesoil thecamming surfaceare diametricallyaligned with the `recess 64 and the teeth at 65; in cam 49 the highzones' of the camming surface are displaced ninety degrees therefrom.

The cylinder block 49 'iS rotated by a shaft'66' journaled in bearings61 and 68.l The'bearingy Slis mounted in a recess in the right-hand endofpintle A45, as indicated in Fig. 1, and the bearing 68 'is a ballbearing mounted Ain therecess -36 of -thevhousing'section 32. Shaft 66is driven by appropriate connectionsto a motor. 'Thefdriving connection`between' the left-hand part of the' shaft/66 and the cylinder block 49is aorded by a driver 69 keyed to thev cylinder block by -drive pins 10(five shown in Fig. v5) The driver 69qhas.

a splined connection to the shaft 66 as indicated at 66', andthe driveris positioned axially by the bottom of the-counterbore 35 in the fronthousing lsection 32 (see the lower vright-handpart oi Fig. 1).

thefront housing 32. An annular spacer k'H performs a similar functionwith respect to the rear housing section 22. The front cover plate 42 isprovided with a bore to support 'andposition parts`j1ll,"15'and 16 (Fig.1), of which 'I4 "is described as acontrol piston and `'l5 vis ah'andwheel forturningjtherod 16 which positions control piston; Thecontrol piston 14 is longitudinally guided bythealigned bores 29, I9 and3'l `within the;lrou'sin'gsectionsA and it is provided'near its oppositeends with helical gear tooth sectors 11, 'Il meshing with the cam geartoothsectors 65, -'ofithe'cams 39and 40 (Figs. 1 and 5). The controlVpistonV is movable longitudinally by the rotation'of the control rod'I6 the right-hand portion 16'- {'of which is provided with screwthreads oactin'g" with internal screw threads V13 ina bore-ofthe-control piston. The handwheel 15 forturning thev rod 16 is providedwith appropriate'graduations or indicia to show the position -ofthecontrol piston. The rod 'I6 is also provided with a iiange or collarr16awhich, in cooperation'with'a face of the handwheel and the interposed'cover plate 4I will position-the rod against raxial movement.

In turn, the driver'69 restrainslthe. cylinder block 49 from movingaxially toward' The gear sectors`65` and Il have: helicalteetli,preferablyl about forty-live degree helixia'n'gles` bearing against itsYrespective stop. pin 62. `The.` control piston is notv keyed 'againstrotationabout' itsown axis.A

In Fig. 11 of the'drawings there is shownan enlarged'centrallongitudinal section of one'of the twenty pistons' 56'ofthe Fig. 1assembly. The body of the piston' is considered as tubular, having theWorking portion`51 'formed' integrally with the head portionl 5S "oflarger diameter. The portion 58 serves as a crosshead to support andguide the outer'end ofthe pistOn,"an'd`it:is provided with a sphericallysurfaced f socketfto receive' the-'ball driver 59, which mayfunctionally be considered as a piston head'. Thes'ocketi's relieved as`at r to a diameter substantiallyfequal.' to theexternal diameter 'ofthef piston'fportion! 5l.'y The bore 51 receivesone end of the ,pistonireturn spring 60 (Fig. 1). The openingor'space* t within the main bodyof the pistonportion 5:1? communicates with the space at r throughith'eopeningk q so that fluid under 'pressure' from'the cylinder bore fillsvthe piston space at'r, q, andt;

and exerts its pressure 'directly against the ball 59. vSince the ballarea`exposed to thisiluid pressure is substantially `equal to thecross-sec-V tional area of the workingportion 57 `of itheipis-VA ton,substantially allof the hydraulic lloadfagainst the piston is 'carrieddirectly by the ball.- The axial load taken bythespheri'cal seatsurfaceu consists of the force exertedby 'the spring -69' plus the forcerepresented by theproduct ofthe unit fluid pressure `and the differencebetween the overall cross-sectional area-of Athe piston porf tion 51andthe Iarea of the ball exposed directly to iluid pressure within thepiston. Inadditionv to this residual axial'load' consideration .mustbegiven to the transverse force components due to the'rolling of theballon the inclinedcamsurface.

The total force between the cam and -th'e ball." 59 may be representedby the vector x at a'nangler of inclination w. The axial component 6fmis y1,

most of which is counterbalanced'byfthe 'uidpressure effective on ball59 through opening lp',

and only a little of which has'to be carried 'byl seat surface u. Thetransverse component 'f' is e directed at right angles to the pistonaxis and substantially toward the sphericallysurfacedA seat u. From thisanalysis, and the-'- disclosure in the drawings- (Figs. 1 and 11), itwillappear that the spherical seat is not undulyloaded'feitherA` axiallyor transversely. The axial `load on the spherical seat is relativelysmall, andthe" seatv has a wide and'ample bearing surface tov'withistand the transverse force component. lThe ballV will thereforeroll freely in thesocket and, at the same time, it will seall the socketagainst fluid leakage. This is particularly apparent whenit isconsidered that the bearing surface 'between' the face of the socket 'uand the ball 59 isalwa'ys well supplied with fluid under high4V pressuretol serve as a-lubricant.

In operation, the loaden the piston' 56l` is rap'g-xv idly changed fromhigh to low pressure, and the direction and magnitude of the transverseforce components are also changing. These changes occur rapidly during apiston movement of sixty cycles per second (for example) and insureample renewal of the lubricant between the ball and its seat. The balland seat construction is also such that there is automatic compensationfor wear.

Each of the springs 60 has its opposite ends seated Within the bore ofpiston portions 51, 51 of opposed pistons 56, 56 as indicated in Fig. 1;and each spring, therefore, causes the two pistons to be constrained tofollow the contours of the cams 30 and 40, respectively. With theconstruction shown, the forces required to accelerate the pistons tomake them follow the cam contours are well within safe values which canbe attained by springs fitting the spaces provided by the pistons. Forexample, a driving speed of 1725 R. P. M. requires a maximum springpressure of the order of thirty pounds.

By further reference to Fig. 1 it will be noted that annular grooves 80in the cylinder bores are in communication with the central housing boreI6 through openings 8|, the cylinder block being drilled to provide thelatter openings or passages. They permit a free flow of fluid to andthrough the enlarged outer ends of the cylinder bores I to accommodatethe pumping effect of the crossheads 58. The cylinder block is providedwith annular channels as at 82 (one shown) for rotating clearance forthe driving lobes of the cams 30 and 40.

The space adjacent to the cams 3Q, 40 and the space between the housingand the cylinder block 49 may be kept lled with the oil or other fluidbeing pumped. In this case valve 83 is kept closed. The aforesaid spacemay, however, be kept dry by keeping valve 83 open and constantlydraining any excess oil through pipe 93 to the sump or other fluidreservoir.

The above-described construction including the ball driver and thecoacting piston construction presents a thrust transmitting means whichreduces the real bearing force to a fraction of the value which might besupposed. This results in low friction loss and greatly reduced wear. Inturn these results contribute to the high efficiency of the pump whenoperating at greatly increased pressures. They also contribute to longoperating life. jor portion of the hydraulic force on the pistonand-ballis imposed directly on t -e ball, which rolls on the cam; and, in asense, the part which has been called a piston is not a piston butserves as a guide for the ball and as a packing between the ball and thecylinder bore. This advantageous thrust transmitting construction alsoprovides a high degree of freedom in the designing of cam contours, andin ranges of hydraulic pressure not heretofore possible.

In the illustrative pump each piston moves in a cycle of constantmagnitude; and since the stroke of the piston is never varied, anyreduction in the effective displacement must appear elsewhere in thecycle. Angular phase adjustment of one cam with respect to the other, ineffect, causes a so-called subtraction from what may be termed theeffective pumping stroke of the cycle. This phase adjustment also causesthe conversion of the subtracted portion of the stroke to a motor strokewhich returns to the inlet or supply line an amount of uid equal to theamount subtracted from the outlet. This so-called subtraction is anadvantageous way of reducing the total rate of flow since the return ofIn this construction the mafluid to the inlet is a motor stroke andthere is no loss of energy. The net power taken by the pump isproportional to the net output of fluid under pressure. If the phaseadjustment is sufficient to cause a subtraction in effectivedisplacement equal to one-half the maximum effective displacement(geometrical displacement) the net output is then zero. Further phaseadjustment in the same direction causes the flow to reverse, and as thephase adjustment is continued in the same direction the reverse ilow isincreased to maximum.

A corollary of this principle of variable flow is that the length ofseal between the inlet and outlet ports is maximum at zero flow, andnear maximum at small rates of flow in either direction. This isparticularly advantageous where it is desired to pump accurately atsmall rates at high pressures to effect such results as slow heavy cutson machine tool feed applications.

A better understanding of the operation of the illustrative pump may behad from reference to Figs. 12 and 13. Fig. l2 is a developeddiagrammatic representation of various successive positions of a pair ofpistons in one cylinder bore. Since all pistons execute two identicalpumping cycles per revolution only one cycle of degrees is represented.The pistons are indicated at increments of eighteen degrees of cylinderblock rotation, the center lines of the pistons in the successivepositions being denoted by the reference characters a, b, and c, etc.The cylinder bores are represented by transverse zones A, B and C whereA is the central cylinder bore section between the annular ports 50 and54 and B and C are the two outer guide sections of the cylinder bore. Dand E represent the two ports 50 and 54'. The stationary cams arerepresented by the curves C1 and C2, in which curves the dotted linesindicate the path of the center of the ball driver 59 and the solidlines the` developed cam profile required to produce the dotted linemotion.

Starting at the left, the dotted line C1 from a to c represents athirty-six degree dwell of the piston P1. From c to d, this dotted lineindicates a constant inward acceleration of piston Pi during eighteendegrees of rotation of the cylinder block 49. The dotted line C1 from dto f represents constant inward velocity of the piston P1 duringthirty-six degrees of rotation of the cylinder block. From ,f to g, thepiston P1 has a constant inward deceleration during eighteen degrecs ofthe cycle; and in the next part of the cycle from g to h the piston hasan eighteen degree period of constant outward acceleration. From h, to7', there is a thirty-six degree period of constant outward velocity.From i to a, there is an eighteen degree period of constant outwarddeceleration.

The dotted line or curve C2 represents the movement of opposed piston P2during the cycle just traced for piston P1. Line g indicates the pointon cam curve C1 where the piston P1 is advanced to its farthest inwardposition; and m indicates the point on cam curve C2 where the piston P2is advanced to its farthest inward position. Lines b-b' and n n arecenter lines at which the pistons P1 and P2, respectively, have theirfarthest outward positions. The distance q between n-n and g-g is thephase displacement between the two cams from the position where the netflow is zero. When n n coincides Assu-rnethatthe motion 'of thecylinderblock is to thelright'(Fig.`12) as indicatedY by the arrows q isnegative (as is indicated in Fig. 12),then`.

D is the inlet'port and E is the outlet port. If q is positive, E is theinlet' and. Dis the outlet.

Considering the successive positions of the pistons'as the cylinderblock rotates froma to y', it will beseen that the piston P1 dwells froma to c, and starts moving under constant acceleration at c. At d thispiston has moved enough to close the port D. At m the piston Pz startsits outward movement, creating a suction v'stroke up to the position Yd.Atthis time the port D is closed. From 'd tok-7c both pistons'moveatthefsame constant 'velocity and at 7c the outlet'port-E starts toopen. The piston Pz decelerates from 1c to a and'thenv dwells forthirty-six degrees. The

other piston P1 follows through to gfproducing a pressure or outputstroke.

From g to h the piston P1 is accelerated outwardly, and at l-Z thepiston P2 has vfollowed to point of closing the outlet port E.- FromIf-Z to lg-/j the-two-pistons move 'together with no relativedisplacement. Thus it will be seen that during the Z-Z to :i-i portionof the cycle ythe two pistons have trapped and are returning a certainquantity'of'liquid from the outlet port to Ythe inlet port. A Sportion.ofVv this trapped liquid corresponds to the minimum distance betweenVVthe two pistons; apparent at g--g' and the remainder corresponds tothe.distance that-thepiston `P1 withdraws inthe period h--h tol-l. This disltance h--h to -Z-Z is always equal to-the difference between eighteendegrees and the value of q. If '(1 is made smaller, Athen h to Z becomeslarger and, similarly. the eiectiv'e displacement of uid from D to Ebecomes smaller and the return displacement from E to D becomes larger.

This can be visualized by assuming a gradual movement of the cam curveCz to the right relative to the 'cam'curve C1.

In adjusting for various ratesor 'forward ilow,`

it is 'preferable to hold one cam"'stationary .in

thepump .casing and shift the otherone to 'oh-4 tain thephasedisplacement between cams. In adjusting for-various ratesV ofreverse'lomit is preferable'to hold the-second'cam stationaryin the pumpcasing and shiftthe rstone to'obl The reason for this may bev understoodfrom reference to Fig. 12`.l With q negative as shown in Fig'.` 12, andE the tain the-phase displacement.

During this interval disclosed; adjustments toV vary` the value `Vof solong Vasd is negative, will shift only cam'Czf while cam C1 will bestayed by its'stop pin 62.v`

When q becomes positive and'D is the outlet,- the torque 'reactiontransfers to stop pin' 62 of'caxny C2. I In adjusting to various valuesof q, with'q positivegcam C1 shifts, while cam C2 is stayed'by its-*stoppin 62.

Thismethod lends itself to execution byex-ltremelysimple controlmechanism.: It is en' f Vtirrelyconsistent with the use of -thecontrolz'piston ,disclosedQand if desired the control pistonfflma'yeflbe "adjusted "byfremote* cont-rol. or: serve vcontrol apparatus. pumpshaft GBbe reversedthe stoppins 62-funcjA tion inthe same manner butagainstthe Vopposite ends of camrecessesrl.' y

Understandingof the-functioning of theillustrated pump may-bepromoted byassuming that the positionsa, c, fe, y, and-z also represent veconsecutive cylinder' bores and ve consecutive pairs of pistons.` Thistaken together `with Fig."

13 will providev'aclear understanding of the uniformity' of flow `atfall' adjustments.

Fig1r-13 is 'a velocity diagram showing theman-` ner'invv whichthefcamsproduce a `uniformfnet rate-0f ilow 'for'4 any .'camadjustment.In -th'is diagram-'allof they velocity lines represent the,eiectsofsev'eral pistons-on the flow to orfrom the'outlet port; vI'hesolid 'lines and the-odd.

numeralsrepresent the--eiectof the P1 pistons A(Fig'. i12) and'the-dotted'lines andl even-numerals A represent the veffect of the P2pistons. Plus values, above the zero-linesfindicate eiective flow towardthe outlet portfand' minus values, below the zero lines; represent-eilectivey flow *awayl fromf the outlet" y Referring, for example,vltoV pistons 5 and 6 (Fig.v 13),f`piston5 maybe' considered as startingto pump iluid into thefoutlet'port E (see Fig. 12)

at lc when the piston-B Vopens the `outlet port. Pistonimoves'=at`fconstantvelocity from lc to f.

At'fit .changestoconstant deceleration', and at g to'constant'reverseacceleration. At h pistonY 5 changestoconstant' reverse velocity.' Theforegoingvelocitypatternl of. piston 5 is represented by'th'e -f'solidvline r5'-5-15-`5 extending from` lc to 4Z. l Th'efiloweiectA of pistony5 must be considered? to `stop'` at.v l whenl 'piston 6 closesqtheoutletfiport Ei Similarly, -piston'G may be con--v sideredvto have a'velocity' effect onthe outlet port" frepresented i by ythe dotted line6--6-6. Velocity curves' may be similarly plotted for fourother-pair'slof-pistons to 'makefa completeA div agram (for ve cylinder-bores and degrees). Thesum of allY of thefcurves will addup to thevheavy straight line SJ Curves for f two different phase'adjustmentsofthe 'cams are shown; this means two diierent--values at q and twodiierent valuesv of Aeiective pump'displacement. l'As the distance k-fis reduced the total i'low falls to .zero, and then increases in thereversedirection'.

The'iiow remains-uniform, however, atany adjustment: 1

The-ccmbinationoten cylinde1` Vbores and" doubleffre'quency camsresults'in balanced forces. Even thef axial accelerating andVdecelerating forcesron -thepistonr add up to zero for each cam,"taken'separately.` Furthermore, all pistons perform two workingstrokesper revolutionand thismakesit possible to reduce the stroke by-one-halfand; infturn,reduce' the lengths of pistons and cylinder Vboresfand theoverall size of thepump.

For the 'purpose/of using the pump in a closed system'where: it isydesirable thatthe system be always lled--with uid to avoid anyentrapment of -air,fa small gear'type"makeup pump' may be mounted`r inthe-front housing-section f 321 and drivenfdire'ctly by the'drive shaft66. The outletH of this pump' may be connected by passages lin thehousingsito both thefmaln inlet and outlet passages `2-I- and v28through appropriate check valvesv located'iny therear housingV section22".' In addi' provided forsthelmakeup pump and preferablylocatedfonthe'kfront:housingsection 32.. Also, an @auxiliary reservoiror sumpmay-:be' providedior Si If the direction offrotation of' the areserve supply of uid, and to permit the cooling of the working fluid.

The manufacturing methods required to build the illustrative apparatusare free from diiiicult types of operations, a preponderance of theprecision machining consisting of cylindrical turning, boring, andgrinding. The only special operations required are in connection withthe production of the spherical seats for the ball drivers and in theproduction of the cams.

The illustrative pump is characterized by pulsationless tlow at all flowadjustments. It is also characterized by the balancing of all hydraulicand inertia forces. This results from the particular construction andarrangement of the cylinder bores, pistons and cams. The relativeproportions of dwell, acceleration, velocity and deceleration in thestructure of the cam result in the complete balancing of all inertiaforces so that these forces on either cam always add to zero in thrustor radial load. These factors minimize vibration and contribute to lowcost, effective operation and long life. For example, because of suchbalancing out of forces the cylinder block rotates with substantially noradial bearing load except its own weight, and with substantially nothrust in either direction. Hence no special bearings are required. Thecams also need no special thrust bearings.

The cylinder block is the principal rotating element. It is driven by asimple stub shaft mounted in its own bearings to eliminate any possibleunwanted load on the cylinder block bearing. The cylinder block rotatesupon a pintle bearing which also contains inlet and outlet fluidpassages registering with annular grooves in the cylinder block. Withthis port arrangement, the annular fluid passages are continuouslyconnected to the same passages in the pintle and they are notalternately connected to inlet and outlet ports. This constructionprovides for the long seal (at least one-half inch) between the annularpassages, and this seal is never broken.

The pintle 45 is required to carry only the weight of the cylinder blockand pistons; and with no additional hydraulic forces it is possible toeffect a very close running fit between the pintle and the cylinderblock, without resort to special bearings.

A pump such as disclosed may be used at all rates of delivery from zero,or near zero, flow to its maximum capacity. As previously indicated,this device has the characteristic that the length of seal between theoutlet and inlet ports is maximum at zero flow and near maximum at smallrates of flow in either direction. For most uses I prefer that theconfronting edges of the inlet and outlet ports be spaced by a distanceequal to at least 50% of the stroke of each piston. With a given pumpthe degree of seal is proportional to the value of q shown in Fig. 12.For most uses I prefer that the maximum value of q shall not exceed anamount corresponding to a seal equal in length to approximately 8% ofthe total stroke of each piston. The maximum seal will correspond to azero value of q and Will be equal in length to 25% of the total strokeof each piston. Expressed in terms of intervals during which valving maytake place, these seal lengths make the displacement eiectively to besuspended a minimum of 2.5% of the total piston cycle for the minimumseal and the minimum interval. At or near zero flow the effectivedisplacement is suspended for an interval of approximately 'l1/2% ofthetotalpistoncycle.

This characteristic is of particular value in many applications where itis desired to pump at extremely high pressures when operating at lowdelivery rates, and where high pressures at high delivery rates are notrequired.

I claim:

1. A pump comprising; multiple cylinder bores and multiple pairs ofrelatively movable pistons, one pair reciprocable in each cylinder bore;a rotatable cylinder block in which the cylinder bores are formed, thecylinder bores having inlet and outlet ports in the sides thereof, thecylinder bores collectively being arranged annularly of the cylinderblock axis and the cylinder bores individually being disposed with theiraxes parallel to the cylinder block axis; means to rotate the cylinderblock; and means for reciprocating all of the pistons as the block isrotated, said last-men tioned means including a pair ofnormally-stationary cams and springs operative to bias the pistonstoward the cams, a piston of each pair alternately covering anduncovering an inlet port and the other piston of each pair alternatelycovering and uncovering an outlet port.

2. A pump as in claim l in which there are means to adjust at least oneof the cams to vary the effective displacement of the pump perrevolution of the cylinder block.

3. A pump as in claim l in which there are means to reverse thedirection of pumping flow while the cylinder block continues to rotatein the same direction.

4. A pump as in claim l in which there are means to vary the effectivedisplacement of the pump per revolution of the cylinder block whilemaintaining constant the stroke of all the pistons.

5. A pump as in claim 1 in which the cams move the pistons of each pairto change the space between the pistons during the suction and dischargestrokes and maintain said space constant during an intervening interval.

6. A fluid displacement device comprising: multiple cylinder bores andmultiple pairs of relatively movable pistons, one pair reciprocable ineach cylinder bore; a rotatable cylinder block in which the cylinderbores are formed, the cylinder bores having separate inlet and outletports in the sides thereof; and means to reciprocate the pistons as thecylinder block rotates, said means including a pair ofnormally-stationary cams and springs operative to bias the pistonstoward the cams, the pistons covering and uncovering said ports andthereby effecting the cylinder valving.

7. A fluid displacement device as in claim 6 in which one piston of eachpair covers and uncovers an inlet port and the other piston of each paircovers and uncovers an outlet port.

8. A uid displacement device as in claim 6 in which the cylinder blockhas an annular groove communicating with the inlet ports of all cylinderbores and has a Second annular groove communicating with the outletports of all cylinder bores, and the device is provided with a pair ofiiuid passages, one in constant communication with each of said grooves.

9. A fluid displacement device as in claim 6 in which there is a pintleon which the cylinder block rotates, the block is provided with anannular groove communicating with the inlet ports of all cylinder boresand with a second annular groove communicating with the outlet ports ofall cylinder bores, and the pintle is provided with fluid passages inconstant communication with Said groaves. -1

Vand reciprocates the latter in'a cylinder bore,

and the cylinder bore is connected to an inlet passage during an intakestroke and is connected to an outlet passage duringa dischargeA stroke;

the improvement which comprises: the; piston means being tworelativelymovable pistons, and the rdrive means moving the pistons incoordinated relationship for changing the space between the pistonsduring the suction and discharge strokes and maintaining said spaceconstant during an intervening interval.

12. A uid displacement device as in claim 6 in which the confrontingedges of the inlet and outlet ports are spaced by a distance equal to atleast 50% of the stroke of each piston.

13. A uid displacement device comprising: a cylinder bore having a rstdiameter for a portion of its length and an enlarged diameter for theremainder of its length, a piston in said bore, the piston having trunkportions of rst and enlarged diameters received by the rst and enlargeddiameter portions of said bore, a spherically-surfaced seat formed inthe piston portion of enlarged diameter, a ball tted to said seat, saidball having a diameter approximately equal to said rst diameter, and acam engaging the ball and operative to move the piston in the cylinderbore, the piston having a passage through which the uid pressure fromthe first diameter portion of the cylinder bore is communicated directlyto the ball to reduce the pressure between the seat and the ball.

14. A uid displacement device comprising: multiple cylinder bores andmultiple pairs of relatively movable pistons, one pair reciprocable ineach cylinder bore; a rotatable cylinder block in which the cylinderbores are formed, each cylinder bore having an inlet port in the sidethereof and having a separate outlet port in the side thereof, the inletand outlet ports for each bore being spaced lengthwise of the bore; andmeans to reciprocate the pistons of each pair as the cylinder blockrotates and cause one piston of each pair to cover and uncover an inletport and the other piston of each pair to cover and uncover an outletport, said means including a pair of normally-stationary cams andsprings operative to bias the pistons toward the cams.

15. A fluid displacement device as in claim 14 in which the device isprovided with an inlet passage connected at all times to all of saidinlet ports and with an outlet passage connected at al1 times With allof said outlet ports.

16. A fluid displacement device as in claim 14 in which one cam movesone piston of each pair and the other cam moves the other piston of eachpair, and the curves of the cams are so coordinated that when both theinlet and outlet ports of a cylinder bore are covered the pistons movein the bore at constant spacing.

17. A fluid displacement device as in claim 14 in which the means toreciprocate the pistons so coordinates the piston movements that the sumtotal of the instantaneous rate of effective piston displacements in allof the bores remains constant.

T4 18. A uid. displac ment` device comprising: multiple cylinder boresand multiple pairs of relatively movable pistons, one pair reciprocablein each cylinder bore; a .cylindenblock in Which the cylinder bores areformed, the cylinder bores having inlet and outlet ports in the sidesthereof,

vthe Vcylinder bores collectively being 'arranged annularly ofthe-cylinder block axis and--the cylinder Lbores -individually beingdisposed with their-axes parallel to the cylinder block axis :andmeansinclud-ing a pair of Vcalms-for reciprocating 4all of lthepistonsupon relative rotation between Vthe cylinder block and the cams,the cams movg ing the pistons of each pair to :change thegspace'betweenithe pistons during theV suction and discharge strokes andmaintaining said space constant during an intervening interval, a pistonof each pair alternately covering and uncovering an inlet port, and theother piston of each pair alternately covering and uncovering an outletport.

19. A iiuid displacement device comprising: multiple cylinder bores andmultiple pairs of relatively movable pistons, one pair reciprocable ineach cylinder bore; a cylinder block in which the cylinder bores areformed, each cylinder bore havingr an inlet port in the side thereof andhaving a separate outlet port in the side thereof, the inlet and outletports for each bore being spaced lengthwise of the bore; and means toreciprocate the pistons of each pair and cause one piston of each pairto cover and uncover an inlet port and the other piston of each pair tocover and uncover an outlet port, said means so coordinating the pistonmovements that the sum total of the instantaneous rate of effectivepiston displacements in all bores remains constant.

20. A iiuid displacement device comprising: multiple cylinder bores andmultiple pairs of relatively movable pistons, one pair reciprocable ineach cylinder bore; a rotatable cylinder block in which the cylinderbores are formed, the cylinder bores having separate inlet and outletports in the sides thereof; means to reciprocate the pistons as thecylinder block rotates, the pistons covering and uncovering said portsand thereby effecting the cylinder valving; and a pintle on which thecylinder block rotates, the block being provided With an annular groovecommunicating With the inlet ports of all cylinder bores and with asecond annular groove communicating with the outlet ports of allcylinder bores, and the pintle being provided with uid passages inconstant communication with said grooves.

21. A fluid displacement device comprising: multiple cylinder bores andmultiple pairs of relatively movable pistons, one pair reciprocable ineach cylinder bore; a rotatable cylinder block in which the cylinderbores are formed, the cylinder bores having separate inlet and outletports in the sides thereof; and cam means to reciprocate the pistons asthe cylinder block rotates, the pistons covering and uncovering saidports and thereby effecting the cylinder valving, the pistons beingprovided with balls which engage the cams, and the pistons beingprovided with passages through which the fluid pressure in the cylinderbores is communicated directly to the balls.

VIRGIL D. BARKEB..

(References on following Page) REFERENCES CITED The following referencesare of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Steinbecker Dee. 1, 1914 SearsApr. 10, 1917 Hutchinson Nov. 4, 1919 Weingartner Mar. 29, 1927 De LeeuwMay 15, 1928 Bedford Nov. 27, 1934 De Stoutz Nov. 17, 1936 Ginn Nov. 24,1936 Whitcomb Feb. 23, 1937 Number Number Name Date Zimmerman Jan. 28,1941 Treer Dec. 30, 1941 Williams Mar. 10, 1942 Holmes Dec. 11, 1945Huber Dec. 25, 1945 Smith Mar. 11, 1947 Parilla et al Oct. 14, 1947Deschamps Dec. 2, 1947 FOREIGN PATENTS Country Date Great Britain Mar.2'7, 1930 France 1927 France Oct. 9, 1939

